One thrust of the Phase II effort will be directed towards building an eye tracker that is fully integrated into the visual testing system being developed. In particular, an eye movement response indicator will be incorporated into a clinical psychophysical technique known as multi-flash campimetry; a rapid and reliable procedure for assessing temporal resolution in 120 points per eye. When implemented, a subject would only have to look at a point that is seen to flicker, rather than respond manually. Furthermore, the acquisition of eye position information would allow fixation to be monitored during the test, and the display to be shifted to compensate for small fixation errors. During Year I, while the tracker is being developed, normative multi-flash data will be collected from eight patient populations as well as from age categorized control groups, using a conventional manual response. During Year II, multi-flash data will be collected from four patient populations and age matched controls, using both manual key presses and eye movements to indicate flicker. This will allow the eye movement response indicator to be validated, and an attempt made to partition sources of visual impairment into their afferent and efferent components.